The present invention is a method of binding a portion of the cholesterol or cholesterol ester present in an aqueous system or suspension. This comprises adding a purified bacterial cellulose to the suspension in an amount sufficient to bind at least a portion of the cholesterol present. The method further comprises orally administering bacterial cellulose to mammals in an amount sufficient to absorb at least a portion of the cholesterol or cholesterol ester present in the digestive tract of the mammal.
Arterial plaque buildup has been identified as a major cause of heart attacks and strokes. There is a high correlation between plaque buildup and serum cholesterol content. It is generally accepted that the level of serum cholesterol can be controlled, at least in part, by diet. Physicians generally advocate reduced intake of foods such as egg yolks and organ meats which are naturally high in cholesterol. However, diet is not the only source of cholesterol which enters the mammalian nutritional cycle. A large portion, in fact many authorities believe the major portion, of cholesterol is synthesized in the liver and gall bladder and enters the digestive system through naturally produced bile. Most of the cholesterol, including that from both bile and natural sources, is present in the form of fatty esters. Natural agents cause this to form a suspension in the aqueous system present in the digestive tract.
Effective medication has recently become available for reducing the serum cholesterol level of seriously hypercholesterolemic people. However, this therapy is presently quite expensive and is not without significant side effects. So this treatment is not useful for serum cholesterol level control of the general population.
Various investigators have touted dietary "fiber" as one means of reducing serum cholesterol in humans. The term "fiber" is actually generic to a number of materials which are physically and chemically quite different and which act quite differently in the digestive tract. Mueller et al, J. Nutrition, 113: 2229-2238 (1983) identify four major components of fiber. These are cellulose, hemicellulose, lignin and pectins. The first three are generally found in association in plant cell walls and are completely insoluble and resistant to degradation by materials normally found in the gut. They principally serve to provide bulk and hold moisture. They may also serve to somewhat decrease transiton time through the digestive system. While results reported in the literature are equivocal, there seems to be a strong consensus that insoluble fiber does not function to reduce serum cholesterol levels.
"Soluble fiber" is broad category for many pectin-like or gum-like plant derived complex carbohydrates. These are actually water insoluble hydrophilic materials that tend to form bulky gels or slippery products in the digestive system. Some of these appear to have a definite, if minor, effect on blood lipids and lipoproteins. The following articles are cited as being exemplary: Ullrich, J. Am. Coll. Nutr., 6(1): 19-25 (1987); Van Beresteyn et al, J. Nutrition, 109: 2085-2097 (1979); Jenkins, Lancet, Dec. 15, 1979, pp. 1287-1290; Storey et al, Amer. J. Clin. Nutr., 31(10): S199-S202 (1978).
In one human study Anderson et al, Federation Proc., 46: 877 (1987) reported that a mucilagenous seed coating generally known as psyllium lowered serum cholesterol by an average of 15% and low density lipoproteins by 21% without affecting high density lipoproteins. Cellulose, used as a control material in the tests, had no effect. Other authors as well report the ineffectiveness of cellulose; e.g., Wilson et al, Arterial Sclerosis, 4(2): 147-150 (1984); Vahouny et al, Lipids, 15(12): 1012-1018 (1980); Storey et al, Ibid.; Vahouny et al, Am. J. Clin. Nutr., 31(10): S208-S212 (1978).
Furda in U.S. Pat. No. 4,223,023 reports that chitosan, used in amounts of 1-10% by weight of food intake, is effective at binding many times its own weight of lipids, preventing their digestion and absorption and promoting their excretion. No clinical data were given, however.
It is evident that there is a pressing need for a dietary supplement that would effectively reduce serum cholesterol levels. Ideally this material would be inexpensive, bland or tasteless, and otherwise chemically neutral or inert. The present inventors have discovered that a previously untried type of cellulose will apparently meet all of these requirements.